upsample

Upsample discrete-time models

collapse all in page

Syntax

sysl = upsample(sys,L)

Description

sysl = upsample(sys,L) resamples the discrete-time dynamic system model sys at a sampling rate that is L-times faster than the sample time of sys (Ts0). L must be a positive integer. When sys is a TF model, H(z), upsample returns sysl as H(zL) with the sample time Ts0 / L.

The responses of models sys and sysl have the following similarities:

  • The time responses of sys and sysl match at multiples of Ts0.

  • The frequency responses of sys and sysl match up to the Nyquist frequency π / Ts0.

Note

sysl has L times as many states as sys.

Examples

collapse all

Open Live Script

Create a transfer function with sample time 2.25 seconds.

sys = tf(0.75,[1 10 2],2.25)
sys =
 
       0.75
  --------------
  z^2 + 10 z + 2
 
Sample time: 2.25 seconds
Discrete-time transfer function.
Model Properties

Create a transfer function with a sample time that is 14 times faster than sys.

L = 14;
sys1 = upsample(sys,L)
sys1 =
 
         0.75
  ------------------
  z^28 + 10 z^14 + 2
 
Sample time: 0.16071 seconds
Discrete-time transfer function.
Model Properties

The sample time of sys1 is 0.16071 seconds, which is 14 times faster than the sample time of sys.

Version History

Introduced in R2008b

See Also

| |